DESCRIPTION: Past research has suggested that teens and young adults with attention deficit hyperactivity disorder (ADHD) may be at greater risk than normal peers for traffic offenses, driving while intoxicated, motor vehicle crashes, and license suspensions and revocations. The original phase of the project undertook a multi-source, multi-level, and multi-method assessment of driving competence, knowledge, decision-making, and adverse outcomes in a large sample of both ADHD (N=105) and control (N=64) teens and young adults. Numerous deficits in basic psychological abilities subserving driving, driving behavior, driving simulator performance, and driver knowledge and rapid decision-making were identified in the ADHD group. Using both self-reports and official DMV records, our study also supported earlier research on the greater citation and accident risks associated with ADHD. Severity of ADHD symptoms and frequency of alcohol use and drunkenness were among the best predictors of citation and crash risks. The present application is a two-year competing renewal designed to extend the investigators' research on driving risks to the next logical step by addressing two important questions: 1) Can these driving deficiencies and related risks associated with ADFID be effectively treated with stimulant medication?; and 2) does the use of alcohol before driving produce a differentially greater adverse impact on driving performance in ADHD than in normal peers? Two studies are proposed to address these issues. Study I will use a within subjects reversal design to examine the efficacy of two doses of Adderall (5mg and 10mg) and a placebo on 90 ADFID teens/young adults using a multi-method multi-level battery of driving measures including a new, state-of-the-art driving simulator not available to our prior project. Study II will compare 78 ADFID and 78 control young adults using a within-groups design for the effects of two different doses of alcohol and a placebo on driving performance using the same assessment battery. Results will have substantial clinical import concerning possible effective treatments for driving risks in ADHD youth and the adverse impact of alcohol consumption on driving in ADHD young adults.